There are various environments wherein it is desirable to control the opening and closing of a rotary valve, such as a butterfly valve, in a particular sequence or program. This is particularly true in aerospace applications but wherein space and weight parameters are critical. In just one example, a bleed valve may be used to modulate the discharge of compressor air to ambient during engine transients.
A common approach to actuating rotary valves is to use rotary actuators which can be designed with gear trains, including elliptical gears or the like, for providing a rotational sequence or program for the rotating valve.
A problem with such prior valve actuators is that they are quite complicated, require heavy components such as gears, have large packaging requirements and, in essence, simply are not desirable for aerospace or aircraft applications.
This problem further is magnified when it is desirable to actuate a rotary valve from a fully closed position to a fully opened position and back to the closed position during a single portion of the valve actuating program.
This invention is directed to solving these problems by providing a valve actuator which is unique in its simplicity for carrying out a rather complicated opening and closing program for the rotary valve.